| 摘要 |
PURPOSE:To produce ferromagnetic metallic powder having an oxide film which is good in oxidation resistant stability by dispersing surface-oxidized ferrous ferromagnetic metallic powder into an org. solvent and subjecting the powder to a heating treatment in an inert gas. then allowing the powder to contact an oxygen-contg. gas. CONSTITUTION:The ferromagnetic metallic powder essentially consisting of iron is allowed to contact the oxygen-contg. gas in the org. solvent or gaseous phase to oxidize the surface thereof. The above-mentioned powder is then dispersed in the org. solvent and is subjected to the heating treatment for 0.5-24hr, more preferably 1-5hr at 80-300 deg.C, more preferably 90-200 deg.C in the inert gaseous atmosphere of >=1 kinds of N2, He, Ar, and Ne. The above-mentioned powder is allowed to contact the oxygen-contg. gas again in the org. solvent or gaseous phase to form the uniform and dense oxide film on the surface of the above-mentioned powder. An inert org. solvent such as benzene is preferably used for the above-mentioned org. solvent at >=2 times the pts.wt. of the above-mentioned powder. A gaseous mixture prepd. by diluting air or O2 with N2, He, Ar, Ne, etc. is adequate for the above-mentioned oxygen-contg. gas. |
